This slippery slope is real. Sacrificing a little privacy for one thing does make it seem more acceptable to sacrifice a little more for something else, so forbidding yelling fire in a crowded theater makes it easier to swallow national security letters, and accepting cameras at dangerous intersections makes it easier to accept cameras at every street corner. Making a "reasonable" compromise shifts the bounds for what is reasonable.
That Wikipedia page you linked seems more pointed to social issues (segregation, abortion, etc). It certainly doesn't apply in the cut and dry manner that you suggest; anyone who thinks that making it illegal to cause public panic is a good idea loses all credibility.
Causing public panic by, for example, writing pamphlets against the draft.It certainly doesn't apply in the cut and dry manner that you suggest; anyone who suggests that making it illegal to cause public panic is a good idea loses all credibility.
...causing public panic by yelling 'fire' in a theater or 'bomb' in an airport. Look, if everyone thought the same way as I did, I would say chuck the Constitution out and let's apply common sense! But they don't, and we can't. So sometimes we need laws about things like what you can say in a public place. This is a pity, but it is what it has to be. And yes, I agree by and large with the clear and present danger test. Do I like it every time? No. Do I acknowledge it has to exist? Yes.